Abstract Besides aspect ratio AR and excitation wavelength λ, material composition is also key parameter determining figure of merit (FOM) of individual Au x Ag 1 − x ( x = 0 , 0.2, 0.3, 0.5, 0.7, 0.8,1.0) alloy nanobars. In this paper, the corresponding x dependent refractive-index sensitivity factor (S) and FOM responses were numerically investigated as functions of AR and λ by discrete dipole approximation. It demonstrates that S increases nonlinearly/linearly with λ LSPR / A R for all x concerned while FOM achieves x dependent optimum at optimized λ LSPR and AR. With x decreasing, S, FOM and optimal FOM are revealed to increase. The obtained S and FOM responses are analytically explained well by alloy dielectric response under dipolar LSPR condition. The surrounding medium effect on S and FOM response of optimized Au x Ag 1 − x nanobar is discussed as well. The present work provides significant guideline for future Au/Ag based applications in plasmonic sensing and detection.

中文翻译：

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用于等离子体传感的单个 Au Ag1− 合金纳米棒的最佳纵横比和激发光谱区域

摘要 除了纵横比 AR 和激发波长 λ，材料成分也是决定单个 Au x Ag 1 − x ( x = 0 , 0.2, 0.3, 0.5, 0.7, 0.8,1.0) 合金纳米棒品质因数 (FOM) 的关键参数. 在本文中，相应的 x 相关折射率敏感因子 (S) 和 FOM 响应通过离散偶极子近似作为 AR 和 λ 的函数进行了数值研究。它表明，对于所有相关的 x，S 随 λ LSPR / AR 非线性/线性地增加，而 FOM 在优化的 λ LSPR 和 AR 下实现 x 相关最优。随着 x 的减小，S、FOM 和最佳 FOM 显示增加。在偶极 LSPR 条件下，合金介电响应很好地解释了获得的 S 和 FOM 响应。还讨论了周围介质对优化的 Au x Ag 1 - x 纳米棒的 S 和 FOM 响应的影响。目前的工作为未来基于 Au/Ag 的等离子体传感和检测应用提供了重要指导。